Microorganisms, in particular Streptomyces sp. produce a number of antibiotics including clavulanic acid and other clavams, cephalosporins, polyketides, cephamycins, tunicamycin, holomycin and penicillins. There is considerable interest in being able to manipulate the absolute and relative amounts of these antibiotics produced by the microorganism and accordingly there have been a large number of studies investigating the metabolic and genetic mechanisms of the biosynthetic pathways [Domain, A. L. (1990) “Biosynthesis and regulation of beta-lactam antibiotics.” In: 50 years of Penicillin applications, history and trends]. Many of the enzymes which carry out the various steps in the metabolic pathways and the genes which code for these enzymes are known.
Clavams can be arbitrarily divided into two groups dependent on their ring stereochemistry (5S and 5R clavams). The biochemical pathways for the biosynthesis of 5R and 5S clavams have not yet been fully elucidated but it has been suggested that they are derived from the same starter units (an as yet unidentified 3 carbon compound [Townsend, C. A. and Ho, M. F. (1985) J. Am. Chem. Soc. 107 (4), 1066-1068 and Elson, S. W. and Oliver, R. S. (1978) J. Antibiotics XXXI No. 6, 568] and arginine [Valentine, B. P. et al (1993) J. Am. Chem. Soc. 15, 1210-1211] and share some common intermediates [Iwata-Reuyl, D. and C. A. Townsend (1992) J. Am. Chem. Soc. 114: 2762-63, and Janc, J. W. et al (1993) Bioorg. Med. Chem. Lett. 3:2313-16].
Examples of 5S clavams include clavam-2-carboxylate (C2C), 2-hydroxymethylclavam (2HMC), 2-(3-alanyl)clavam, valclavam and clavaminic acid [GB 1585661, Rohl, F. et al. Arch. Microbiol. 147:315-320, U.S. Pat. No. 4,202,819] There are, however, few examples of 5R clavams and by far the most well known is the beta lactamase inhibitor clavulanic acid which is produced by the fermentation of Streptomyces clavuligerus. Clavulanic acid, in the form of potassium clavulanate is combined with the beta-lactam amoxycillin in the antibiotic AUGMENTIN (Trade Mark SmithKline Beecham). Because of this commercial interest, investigations into the understanding of clavam biosynthesis have concentrated on the biosynthesis of the 5R clavam, clavulanic acid, by S. clavuligerus. A number of enzymes and their genes associated with the biosynthesis of clavulanic acid have been identified and published. Examples of such publications include Hodgson, J. E. et al., Gene 166, 49-55 (1995), Aidoo, K. A. et al., Gene 147, 41-46 (1994), Paradkar, A. S. et al., J. Bact. 177(5), 1307-14 (1995). In contrast nothing is known about the biosynthesis and genetics of 5S clavams other than clavaminic acid which is a clavulanic acid precursor produced by the action of clavaminic acid synthase in the clavulanic acid biosynthetic pathway in S. clavuligerus. 
Gene cloning experiments have identified that S. clavuligerus contains two clavaminic acid synthase isoenzymes, cas1 and cas2 [Marsh, E. N. et al Biochemistry 31, 12648-657, (1992)] both of which can contribute to clavulanic acid production under certain nutritional conditions [Paradkar, A. S. et al., J. Bact. 177(5), 1307-14 (1995)]. Clavaminic acid synthase activity has also been detected in other clavulanic acid producing micro-organisms, ie. S. jumonjinensis [Vidal, C. M., ES 550549, (1987)] and S. katsurahamanus [Kitano, K. et al., JP 53-104796, (1978)] as well as S. antibioticos, a producer of the 5S clavam, valclavam [Baldwin, J. E. et al., Tetrahedron Letts. 35(17), 2783-86, (1994)]. The latter paper also reported S. antibioticos to have proclavaminic acid amidino hydrolase activity, another enzyme known to be involved in clavulanic acid biosynthesis. All other genes identified in S. clavuligerus as involved in clavam biosynthesis have been reported to be required for clavulanic acid biosynthesis [Hodgson, J. E. et al., Gene 166, 49-55 (1995), Aidoo, K. A. et al., Gene 147, 41-46 (1994)] and as yet none have been reported which are specific for the biosynthesis of 5S clavams.